Elbow mandrel arrangement

ABSTRACT

A mandrel arrangement for mounting a pipe machining tool for rotation relative to at least one end of a pipe elbow or other bend to be machined. A mandrel frame is provided with first and second flange portions having outer surfaces located within planes which intersect to form a predetermined angle approximately equal to the angle of the pipe bend. The frame is adapted to be positioned within the pipe bend with an outer surface of the first flange portion adjacent a first end of the pipe bend and an outer surface of the second flange portion adjacent a second end of the pipe bend. A locking means connected to the mandrel frame is adjustable between a first radially retracted condition in which the frame is free to move relative to the pipe, and a second radially extended condition in which the frame exerts an outward force against the interior of the pipe to frictionally retain the frame from movement relative thereto. A mandrel shaft means adapted to receive the pipe machining tool for relative rotation about its axis is adjustably mountable to the first flange portion such that the mandrel shaft means extends perpendicularly from the outer surface thereof and is adjustable between a plurality of positions adjacent the center of the first end of the pipe bend. The mandrel shaft means may thus be adjusted to coincide with the center of the first end of the pipe bend to receive the pipe machining tool for relative rotation thereabout. The mandrel shaft means may be similarly adjustably mountable to the second flance portion to allow machining of the two ends of the pipe bend relative to axes which intersect to form an angle equal to the predetermined angle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the pipe machining art and more particularlyto an improved mandrel arrangement useful in mounting a pipe machiningtool for rotation relative to at least one end of a pipe bend to bebeveled or otherwise machined.

2. Description of the Prior Art

Many pipe machining tools are designed to be rotated about the centerline of a pipe to accomplish a machining operation on the pipe. Twoexamples thereof are described in U.S. Pat. No. 3,875,832, issued Apr.8, 1975 entitled Manual Pipe Bevelling Tool and U.S. Pat. No. 3,927,584issued Dec. 23, 1975 entitled Pipe End Facing and Grooving Machine. U.S.Pat. No. 3,875,832 discloses a manual tool to be rotated about the axisof a pipe adjacent its end for the purpose of cutting a bevel thereon.U.S. Pat. No. 3,927,584 discloses a tool the cutting assembly of whichis adapted to rotate about the axis of a pipe to machine a square faceand an external annular groove on the end of the pipe for the receptionof a pipe coupling element.

In tools of this type, a mandrel is required to mount the tools forrotation. Since the mandrel shaft must be coaxial with the pipe beingmachined, it is easiest to mount the mandrel arrangement directly to thepipe. Such mandrels must be extremely rigid to provide an accurate cutand to withstand the substantial forces placed thereon, but should alsobe able to be installed and removed easily relative to a particularlength of pipe. The ease of installation and removal is particularlyimportant for use in the field, where pipes are machined with a minimumof sophisticated tools and alignment mechanisms. A mandrel must also berelatively inexpensive to justify extensive field use.

Mandrels exist for use with straight sections of pipe, but I am notaware of any mandrel which is truly satisfactory for use in machiningpipe elbows or other bends. U.S. Pat. Nos. 3,875,832 and 3,927,584illustrate mandrels for use with straight sections of pipe comprising aplurality of longitudinally directed radial fins which may be expandedby tightening an axial draw bar, drawing those fins over a set ofradially inclined camming surfaces. The radially outer edges of the finsmay thus be caused to engage the inner surface of the pipe in a clampingrelationship to rigidly fix the draw bar along the axis thereof. Eitherthe draw bar itself or a hollow bar fitted thereover serves as a mandrelfor rotation of the pipe machining tool.

The above-described mandrels are unsatisfactory for use in machining theends of pipe elbows and other pipe bends because pipe bends generally donot possess the length of straight pipe necessary to engage and retainan expanding fin arrangement. The curved inner surfaces of pipe bendspresent unique and previously unsolved problems in securing a mandrel.Mandrels for such use must be accurately and rigidly mountable within apipe bend, and must also be of a simple design allowing quick and easyinstallation.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide animproved mandrel arrangement for mounting a pipe machining tool foraxial rotation relative to an open end of a pipe bend.

It is another object of the present invention to provide an improvedmandrel arrangement which may be fitted within a pipe bend and easilyaligned and secured in place relative thereto.

It is yet another object of the present invention to provide a rigidmandrel arrangement for use in machining a pipe bend, which mandrelarrangement is of a simple design and is relatively inexpensive tomanufacturer.

It is a further object of the present invention to provide an improvedmandrel arrangement for mounting a pipe machining tool for rotationrelative to a pipe bend having two open ends such that the two open endsare machined about two axes, respectively, having a precise angularrelationship relative to each other.

It is a further object of the present invention to provide an improvedmandrel arrangement for mounting a pipe machining tool for rotationrelative to a pipe bend having one open end and a second end connectedto a run of pipe such that the one open end is machined about an axishaving a precise angular relationship relative to the axis of the run ofpipe.

The above and other objects of the present invention are acheived, inthe preferred embodiment, by providing a mandrel frame which may befitted within a pipe bend and secured relative thereto to mount amandrel shaft projecting outward from one end of the pipe bend.

The frame is provided with first and second flange portions fixedthereto and having outer surfaces which are located within planes thatintersect to form an angle equal to that of the pipe bend. The frame isadapted to be positioned within the pipe bend with the outer surface ofthe first flange portion adjacent to a first end of the pipe bend andthe outer surface of the second flange portion adjacent to a second endof the pipe bend. The frame is provided with a locking means connectedthereto and adjustable between a first radially retracted condition inwhich the frame is free to move relative to the pipe bend, and a secondradially extended condition in which the frame exerts an outward forceagainst the interior of the pipe bend to frictionally retain it againstmovement relative thereto.

A mandrel shaft means adapted to receive a pipe machining tool for axialrotation relative thereto is mounted to the frame such that the mandrelshaft means extends perpendicularly outward from the outer surface ofthe first flange portion and is adjustable between predeterminedpositions adjacent and including the center of the first end of the pipebend. The mandrel shaft means may therefore be adjusted to coincide withthe center of the first end of the pipe bend to receive a pipe machiningtool for rotation thereabout.

The mandrel shaft means may be adjustably mounted to the frame throughan axial threaded portion of the shaft means which engages a firstcaptive nut located within the frame adjacent the first flange portion.The captive nut is restrained by the frame portion against movementrelative thereto, except essentially translational movement betweenvarious radial locations corresponding to the predetermined positions ofthe mandrel shaft means. The mandrel shaft means is therefore movablebetween those positions for the axial threaded portion thereof in anengaged but untightened condition with the captive nut, and is fixed inone of those positions for the axial threaded portion of the mandrelshaft means in a tightened condition.

A simple centering unit may be used to position the mandrel shaft meansalong the center line of the first end of the pipe bend beforetightening it in place. The centering unit may include at least threeradial vanes extending longitudinally of a bearing element adapted toslidingly engage the mandrel shaft means. Each such vane may be providedwith a longitudinal taper adapted to engage the first end of the pipebend in a centering relationship for the fully engaged condition of thecentering unit relative to the mandrel shaft means.

A locating plate removably attachable to the second flange portion maybe provided to abut the second end of the pipe bend from a point outsidethe bend to rigidly locate the mandrel frame relative thereto. Thelocating plate may be generally circular in shape and include aplurality of projections which are adjustable in length and arepositioned to space a portion of the generally circular locating plate adesired distance from the second end of the pipe bend. The orientationof the frame relative to the second end of the pipe may thus be variedsomewhat to adjust to a badly framed fitting by adjusting the lengths ofthe projections.

The locking means used to fix the mandrel frame relative to the pipebend may comprise a screw thread mechanism adapted to force at least onemovable locking element against the interior of the bend. The screwthread mechanism may include a pair of movable locking elementsconnected by a single bolt for actuation of the locking elements inopposite directions for engagement with the pipe bend. The bolt mayextend between the two flange portions such that the angles formedbetween the axis of the bolt and first flange portion is similar to thatformed between the axis of the bolt and the second flange portion.

A second captive nut identical to the first captive nut may be locatedwithin the mandrel frame adjacent the second flange portion. The secondcaptive nut is restrained against relative movement, except a limitedamount of essentially translational movement between various radiallocations corresponding to predetermined positions of the mandrel shaftmeans relative to the center of the second end of the pipe bend. Themandrel shaft means may therefore be disengaged from the first flangeportion and engaged with the second flange portion in a position whichcoincides with the center of the second end. This may be accomplishedwithout unlocking the frame from the pipe bend. The locating plate maybe secured by a central bolt engagable with the two captive nuts. Afterone end of a particular pipe bend has been machined using the mandrel ofthe instant invention, the locating plate may be removed and the mandrelshaft means applied to the second flange portion. The mandrel shaftmeans is then centered with the centering unit and used to machine thethe second end of the pipe bend. The mandrel arrangement of the instantinvention therefore enables both ends of a pipe bend to be beveled orotherwise machined without removing or relocating the frame. The cutsthus produced are precisely oriented relative to each other.

The mandrel shaft means may include a radial flange adjacent the axialthreaded portion and adapted to insure the perpendicularity of themandrel shaft means relative to the outer surface of the flange portionto which it is attached. A pin projecting downward from the lowersurface of the radial flange may be provided to engage openings in theouter surfaces of the first and second flange portions to prevent themandrel shaft means from rotating after assembly.

In use, the frame is first fitted into the pipe bend such that the firstand second flange portions are adjacent to the planes which include thefirst and second ends, respectively, of the pipe bend. The locatingplate is then attached to the second flange portion of the frame andpositioned flush with the second end of the pipe bend. The mandrel frameis locked in this position by rotating the locking bolt. At this point,the frame is rigidly fixed within the pipe bend with its first flangeportion adjacent to the first end of the pipe bend and its second flangeportion adjacent to the second end of the pipe bend. The threadedsection of the mandrel shaft means is then loosely engaged with thefirst captive nut. The mandrel shaft means thus projects perpendicularlyfrom the first flange portion, and is movable radially relative theretobetween the predetermined positions adjacent to the center of the firstend of the pipe bend. Sliding the centering unit over the mandrel shaftmeans and against the first end of the pipe bend urges the mandrel shaftmeans to the center of the first end. The mandrel shaft means may belocked in this position by tightening the axial threaded portionrelative to the captive nut. The mandrel shaft means is then properlyaligned and secured for use to mount a pipe machining tool for rotationrelative thereto. If it is also desired to machine the second end of thepipe bend, the locating plate may be removed from the second flangeportion and the mandrel shaft means installed thereon. Alignment andtightening of the mandrel shaft means relative to the second end of thepipe bend is accomplished by again sliding the centering unit over themandrel shaft means and tightening the axial threaded portion thereof.This procedure enables both ends of the pipe bend to be easily andaccurately machined for a single placement of the mandrel frame withinthat pipe bend, resulting in machined surfaces which are preciselyoriented relative to each other.

The mandrel arrangement of the instant invention may also be used tomachine an end of a pipe bend whose other end has been welded to a runof pipe. In this case, the frame is fitted within the pipe bend with themandrel shaft means in place thereon such that the mandrel shaft meansprojects outward from the open end of the pipe bend. The mandrel shaftis aligned within a plane perpendicular to the run of pipe with the aidof a squaring guage fitted to the run of pipe. Alignment in thedirection perpendicular to that plane is accomplished with a spiritlevel.

The mandrel arrangement of the instant invention may therefore be easilyand accurately installed within a given pipe bend with a minimum ofeffort or tools. This is made possible by its uniquely simpleconstruction and alignment mechanisms, making the arrangement wellsuited to use in the field. The mandrel shaft is also extremely wellsecured within the pipe bend after installation.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects of the present invention may be more fullyunderstood from the following detailed description taken together withthe accompanying drawings wherein similar reference characters refer tosimilar elements throughout and in which:

FIG. 1 is a partially exploded perspective view of one embodiment of thepresent invention installed in a pipe elbow;

FIG. 2 is a partially exploded side elevational view which is partiallybroken away to a vertical section along the line 1--1 of FIG. 1;

FIG. 3 is a front elevational view of the device shown in FIG. 1 withthe centering unit and locating plate removed;

FIG. 4 is a top plan view of the device shown in FIG. 1;

FIG. 5 is a bottom view of the device shown in FIG. 1;

FIG. 6 is a side elevational view of the device shown in FIG. 1 in placewithin a pipe elbow and supporting a pipe beveling tool for rotationthereabout;

FIG. 7 is a side elevational view of the device shown in FIG. 1installed within a pipe elbow fixed at one end to a run of pipe.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings there is illustrated, in FIGS. 1 through 5thereof, a preferred embodiment of the invention generally designated10. The embodiment 10 generally comprises a frame 12, a locating plate14, a shaft apparatus 16 and a centering unit 18. The embodiment 10 isshown in FIG. 1 in place within a 90° pipe fitting, commonly referred toas an "elbow", which is designated therein 20. The pipe elbow 20 isshown with a first open end 22 and a second open end 24 at opposite endsthereof.

The frame 12 comprises a first flange portion 26 and a second flangeportion 28 connected to opposite ends of a main portion 30. Thesecomponents of the frame 12 are desirably constructed of heavy metalstock permanently connected, as by welding. The first flange portion 26and the second flange portion 28 are each circular in shape and arepositioned within perpendicular planes such that the frame 12 may befitted within the pipe elbow 20 with the first flange portion 26adjacent to the first open end 22, and the second flange portionadjacent to the second open end 24. The main portion 30 may beconstructed of somewhat heavier stock than the flange portions 26 and28, and is perpendicular thereto. The main portion 30 is small enough tonot interfere with the inner wall 32 of the pipe elbow 20 duringinstallation and removal of the frame 12 relative to the pipe elbow 20,and is located within the plane about which the pipe elbow 20 issymmetric. The points at which the first and second flange portions 26and 28 are nearest to each other are connected by an edge 34 which islinear between those points and which forms angles of 45° with each ofthe flange portions. The edge 34 is provided with a linear slot 36 ofgenerally square cross-section which passes through the first and secondflange portions 26 and 28 at angles of 45°. The linear slot 36 isadapted to closely receive clamping elements 38 and 40 for slidingmovement of those elements therealong. A locking bolt 42 is disposedlongitudinally within the linear slot 36 and operatively connects theclamping elements 38 and 40. The locking bolt 42 is provided with a headportion 44 and a threaded portion 46 best seen in FIG. 2. The lockingbolt 42 passes through an opening 48 such that the head portion 44 islocated on the side of the clamping element 38 which is nearest thefirst flange portion 26, and the threaded portion 46 engages a threadopening 50 of the clamping element 40. The openings 48 and 50 are bothdirected longitudinally of the linear slot 36 when the clamping elements38 and 40 are in position within the slot. The opening 48 iscounter-sunk at its outer end to receive the head portion 44 of thelocking bolt 42 for the engaged condition of said locking bolt. A boltguide 52 is located within the linear slot 36 at a point midway betweenits two ends. The bolt guide 52 is perpendicular to the axis of thelinear slot 36 and is provided with a guide opening 54 which is adaptedto receive the locking bolt 42 when said bolt is in position within theslot. A pair of spring elements 56 are placed about the locking bolt 42on either side of the bolt guide 52 between the bolt guide and the firstand second clamping elements 38 and 40, respectively. The clampingelements 38 and 40 are thus urged toward opposite ends of the linearslot 36 by the spring elements 56 while being confined to a maximumlongitudinal extension by the condition of engagement of the lockingbolt 42 with the threaded opening 50 in the clamping element 40. Thespring elements 56 in conjunction with the bolt guide 52 also serve tomaintain the clamping elements 38 and 40 in a symmetric relationshiprelative to the bolt guide 52. Actuation of the locking bolt 42 toward acondition of further engagement with the threaded opening 50 thereforeuniformly draws the clamping elements 38 and 40 together along thelinear slot 36. Actuation of the locking bolt 42 in the oppositedirection results in separation of the clamping elements 38 and 40.

The clamping element 38 is provided with an engaging portion 58 whichprojects outward from the linear slot 36 and has an engaging surface 60which is perpendicular to the outer surface 68 of the first flangeportion 26 and faces outward therefrom. The engaging surface 60 thusforms an angle of 45° with the direction of the linear slot 36. Movementof the clamping element 38 along the linear slot 36 therefore results ina component of movement of the engaging surface 60 which isperpendicular to that surface. It is that component of movement outwardfrom the first flange portion 26 which forces the engaging surface 60against the inner surface of the first open end 22 of the pipe elbow 20when the locking bolt 42 is tightened. This outward clamping actionserves to rigidly locate the first flange portion 26 relative to thefirst open end 22. The clamping element 40 is provided with an engagingportion 62 having an engaging surface 64 which is functionally identicalto the engaging surface 60. The engaging surface 64 is locatedperpendicular to the outer surface 84 of the second flange portion 28and faces away therefrom. Movement of the clamping element 40 serves toeffectively move the surface 64 radially outwardly from the secondflange portion 28 to a condition of clamping engagement with theinterior of the second open end 24 of the pipe elbow 20. Actuation ofthe locking bolt 42 therefore serves to clamp the frame 12 into the pipeelbow 20 adjacent both the first open end 22 and the second open end 24.The spring elements 56 allow the entire clamping mechanism to floatrelative to the remainder of the frame 12, thereby enabling both ends ofthe frame 12 to be rigidly clamped by actuation of the single lockingbolt 42. In case one of the clamping elements 38 or 40 becomes seatedagainst the interior of the pipe elbow 20 before the other, the springelements 56 will enable the other clamping element to be furtheractuated to a condition of complete engagement with the pipe elbow 20.

The flange portions 26 and 28 each include a pair of blunt projections66 adapted to engage the interior of the two open ends of the pipe elbow20 for the frame 12 in a clamped condition relative thereto. The use ofthe blunt projections 66 rather than flange portions of slightly largerdiameter enables the frame 12 to more easily clear the interior of thepipe elbow 20 during insertion and removal relative thereto and to spacethe flange portions therefrom.

The flange portion 26 may be generally circular in shape and is providedwith an outer surface 68 which is essentially flat and adjacent to thefirst open end 22 of the pipe elbow 20. The outer surface 68 is providedwith a central enlarged opening 70 extending axially through the firstflange portion 26 and a somewhat smaller eccentric opening 72 parallelthereto. The upper end of the linear slot 36 also extends through theouter surface 68 adjacent one edge thereof. A captive nut 74 is locatedwithin an opening 76 in the main portion 30 of the frame 12 at alocation directly beneath the first flange portion 26. The captive nut74 is provided with a threaded opening 78 the axis of which is parallelto that of the enlarged opening 70. The captive nut 74 is generallyconfined within the opening 76 against axial or rotational movementrelative thereto, but is free for substantially translational movementbetween a plurality of different conditions of registration of thethreaded opening 78 with the enlarged opening 70. The captive nut 74 isretained within the opening 76 by a screw and washer arrangement 80which passes through an opening in the captive nut 74 and is threadinglyengaged with the underside of the first flange portion 26. The openingis enlarged relative to the diameter of the screw 80 to enable theabove-described substantially translational movement of the captive nut74 relative to the opening 76. The screw and washer arrangement 80 areloose enough relative to the captive nut 74 to allow relative movementthereof. A set screw 84 may be provided at the other end of the threadedopening with which the screw and washer arrangement 80 is engaged toallow the screw and washer arrangement to be tightened thereagainstwhile not clamping tightly against the captive nut 74.

The second flange portion 28 may be constructed identically to the firstflange portion 26 described above to provide an outer surface 84adjacent the second open end 24 of the pipe elbow 20 with a centralenlarged opening 86 and an eccentric opening 88 therethrough. A captivenut 90 is provided within an opening 92 in the frame 12 to limitrelative movement of the captive nut 90 to substantially translationalmovement within a plane parallel to the outer surface 84. The captivenut 90 is provided with a threaded opening 94 the axis of which isparallel to the axis of the enlarged opening 86. The captive nut 90 isretained in the opening 92 by a screw and washer arrangement 96 whichpasses through an opening in the captive nut 90 to a threadingengagement with the second flange portion 28. A set screw 100 isprovided to lock the screw and washer arrangement 96 relative to thesecond flange portion 28 without clamping against the captive nut 90.The captive nut 90 is therefore movable between a plurality ofconditions of registration with the enlarged opening 86.

The shaft apparatus 16 generally comprises a shaft element 102 having anaxial opening 104 adapted to receive a draw bar bolt 106 from its upperend. The shaft element 102 includes a radial flange 108 having a lowersurface 110 which is perpendicular to the axis of the shaft element 102.The draw bar bolt 106 may be provided with a hex head 112 at its upperend and is sufficiently long to extend entirely through the axialopening 104 and project a distance past the radial flange 108 which isgreater than the thickness of the first and second flange portions 26and 28. The draw bar bolt 106 is threadingly engageable with thethreaded openings 78 and 94 of the captive nuts 74 and 90, respectively.The shaft apparatus 16 may therefore be positioned with its radialflange 108 against one of the flange portions 26 or 28 to enable thedraw bar bolt 106 to engage one of the captive nuts 74 or 90. The radialflange 108 is provided with a pin element 114 which is engageable withone of the eccentric openings 72 or 88 in this condition, to prevent theshaft element 102 from rotating relative to the frame 12. The draw barbolt 106 may be loosely engaged with one of the captive nuts 74 or 90 toallow movement of the shaft apparatus 16 within a radial plane betweenpositions which correspond to the various positions of said captive nut.The draw bar bolt 106 may be tightened in any one of these positions torestrain the shaft apparatus 16 for further movement. It is clear fromthe above description that the shaft apparatus 16 may be applied toeither the first flange portion 26 or the second flange portion 28 foradjustable attachment relative thereto. The shaft apparatus 16 mayfurther be applied first to one of the flange portions 26 or 28 and thento the other without removing or relocating the frame 12 relative to thepipe elbow 20.

The locating plate 14 comprises a disc 116 having a diameter greaterthan the inside diameter of the pipe elbow 20 and a spacing element 118which is co-axial therewith and has a diameter less than the insidediameter of the pipe elbow 20. The locating plate 14 is provided with anaxial opening 120 which is counter-sunk at its end adjacent the disc 116to receive a bolt 122 extending therethrough. The bolt 122 is adapted toengage the threaded opening 94 of the captive nut 90 for the locating 14positioned against the second flange portion 28. The locating plate 14may be fixed relative to the frame 12 by tightening the bolt 122. Thewidth of the spacing element 118 is designed to cause the disc 116 toabut the second open end 24 of the pipe elbow 20 for the frame 12 in itscondition of proper alignment within the pipe elbow 20. The locatingplate 14 thus enables quick and accurate alignment of the frame 12within the pipe elbow 20 prior to locking the frame 12 therein throughactuation of the locking bolt 42. The locating plate 14 may be providedwith a plurality of adjusting screws 124 threaded through the disc 116at a plurality of circumferential points to contact the second open endof the pipe elbow 20. The adjusting screws 124 may therefore be adjustedto space the locating plate 14 from the second open end 24 as desired tocompensate for a poorly shaped fitting or to machine one or both of thepipe ends at an angle which differs somewhat from the standard. Theadjusting screws 124 may be provided with locking nuts 126 to securethem in a desired position. The bolt 122 may be a cap screw which isretained within the counter-sunk portion of the axial opening 120 by asmall retaining screw 128, to allow rotation of the bolt 122 whileretaining it axially in place within the opening 120.

The centering unit 18 comprises a central annular portion 130 which isslidingly engageable with the shaft element 102 and has three similarcentering vanes 132 extending longitudinally thereof and radiallytherefrom. Each of the centering vanes 132 is provided at its lower endwith a tapered portion 134 to engage the inner edge of an open end ofthe pipe elbow 20 and to urge the shaft apparatus 16 toward the centerof that open end for the centering unit positioned on the shaft element102 with the tapered portions 134 pressed toward the frame 12. Each ofthe centering vanes 132 is provided at its other end with an undercutportion 136 forming a longitudinal inward facing tapered surface whichprogresses radially outward from the annular portion 130 in thedirection away from the remainder of the centering unit 18. The undercutportions 136 are positioned to engage the outer edge of an open end ofthe pipe elbow 20 and to urge the shaft apparatus 16 toward the centerof the open end for the centering unit positioned on the shaft element102 with the undercut portions 136 pressed toward the frame 12. Theshaft apparatus 16 may thus be centered while in a loosened conditionrelative to the frame 12 by merely passing the centering unit 18thereover and pressing it toward the frame 12. The tapered edge of thecentering unit which first contacts the open end of the pipe elbow 20will cause a net radial force toward or away from that point on the openend to be exerted on the shaft apparatus 16. The shaft apparatus willthus be moved to the point where all three vanes contact the open endsimultaneously, at which point the apparatus will be centered relativethereto. The draw bar bolt 106 may then be tightened to maintain thiscondition. The provision of undercut portions 136 as well as taperedportions 134 allows the shaft apparatus to be accurately centered evenif the inner or outer edge of the particular open end of the pipe elbow20 is somehow flawed or out of shape. The centering operation can beperformed accurately if at least one of those edges is satisfactory.

In operation, the frame 12 is fitted within the pipe elbow 20 with theclamping elements 38 and 40 in their radially retracted condition. Thelocking bolt 42 is then actuated to snug the clamping elements 38 and 40against the interior of the pipe element 20 while the frame 12 is heldwith the first and second flange portions 26 and 28 adjacent and roughlyparallel to the first and second open ends 22 and 24 of the pipe elbow20, respectively. The locating plate 14 is then fixed relative to theframe 12 by engagement of the bolt 122 with the captive nut 90. Thelocking bolt 42 may then be loosened slightly to enable shifting of theframe 12 to a condition wherein the locating plate 14 is flush with thesecond open end 24 of the pipe elbow 20. The locking bolt 42 is thensecurely tightened to lock the frame 12 in that condition, wherein theframe 12 is symmetrically located within the frame 12. The adjustingscrews 124 enable the operator either to correct for a malformed pipefitting or set up the embodiment 10 to support a pipe machining tool forrotation along an axis which deviates somewhat from that ordinarilydesired. After the frame 12 is properly secured within the pipe elbow20, the shaft apparatus 16 is loosely engaged with the captive nut 74such that the shaft element 102 projects outward from the first flangeportion 26 along an axis perpendicular to the surface thereof. For aproperly formed pipe elbow and the standard setting of the adjustingscrews 124, the shaft element is also perpendicular to the first openend 22 of the pipe elbow. In this untightened condition, the shaftelement 102 is movable within a radial plane relative to the firstflange portion 26 between a plurality of positions adjacent to andincluding the center of the first open end 22 of the pipe elbow 20. Thedraw bar bolt 106, the pin element 114, and the captive nut 74 are eachfree for limited movement which corresponds to the movement of the shaftelement 102. The centering unit 18 is then fitted over the shaftapparatus 16 such that either the tapered portions 134 or the taperedsurfaces of the undercut portions 136 will contact the open end of thepipe to center the shaft apparatus 16 relative thereto. The draw barbolt 106 may then be tightened to lock the shaft apparatus in thecentered condition. At this point the embodiment 10 is fully installedand aligned, and is ready for use to mount a pipe machining tool forrotation relative to the first open end of the pipe elbow 20. If it isalso desired to machine the second open end 24 of the pipe elbow 20, theshaft apparatus 16 is merely removed from the first flange portion 26and applied to the second flange portion 28 in place of the locatingplate 14. The draw bar bolt 106 is therefore engaged with the captivenut 90 and is centered relative to the second open end of the pipe elbow20 with the centering unit 18.

It can be seen from the above discussion that the embodiment 10 isuseful to mount a pipe machining tool for rotation relative to one orboth ends of a pipe elbow without the necessity for removal orrelocation of its main frame 12 between machining operations. A pair ofmachined pipe elbow ends obtained with the aid of the apparatus 10 aregenerally more precisely perpendicular than two cuts obtained using anapparatus which must be completely readjusted before a second end can bemachined. The double process using the embodiment 10 is also easier andfaster.

FIG. 6 illustrates generally a pipe elbow 20 into which the embodiment10 has been installed and adjusted, and to which embodiment a pipebeveling tool 140 is mounted. The pipe beveling tool 140 is mounted forrotation about the shaft apparatus 16 and includes cutters 142 mountedat an angle relative to the axis of rotation and adapted to engage thefirst open end 22 of the pipe elbow 20. The operator merely rotates thepipe beveling tool 140 manually using the handles 144 to cause thecutters 142 to bevel the first open end 22. A large nut 146 may engage athreaded outer surface of the shaft apparatus 16 near its axially outerend to force the cutters 142 against the first open end 22 as the pipebeveling tool 140 rotates. In this way, the cutters 142 may be advancedaxially relative to the first open end 22 as desired.

FIG. 7 illustrates the embodiment 10 installed within a pipe elbow 148which has been welded at one end to a run of pipe 150. The locatingplate 14 is therefore not able to be used at a second end of the pipe,and the mandrel shaft 16 must be otherwise aligned along the open end152 of the pipe elbow 148. A squaring gauge 154 is used to orient theshaft apparatus 16 in a direction perpendicular to the run of pipe 150.The squaring gange includes a short section of angle iron 156 connectedto a plate 158. The section of angle iron 156 is positioned on thesurface of the run of pipe 150 with the outer edges of its flangeportions receiving that surface and directed parallel to the run ofpipe. The plate 158 has a gauge edge 160 which is perpendicular to thedirection of the angle iron and is adapted to be placed adjacent theshaft apparatus 16 while the section of angle iron 156 is applied to therun of pipe 150. The frame 12 may then be easily adjusted within thepipe elbow 158 such that the shaft apparatus 60 is parallel to the gaugeedge 160 and is therefore perpendicular to the run of pipe 150. This isaccomplished with the locking bolt 42 in a somewhat loosened condition.The alignment of the shaft apparatus 60 is completed with the aid of aspirit level 162.

While the above detailed description deals on its face with a mandreladapted for use in a pipe elbow having an angle of 90°, the descriptionis equally applicable to pipe "bends" of other angles. the criticaldistinction in cases of pipe bends not equal to 90° is the difference inthe angle between the first flange portion 26 and the second flangeportion 28. That angle is then equal to the angle of the fitting towhich it is to be applied, with the first flange portion adjacent to thefirst open end of the pipe bend and and the second flange portionadjacent to the second open end of the pipe bend for the framepositioned within the pipe bend. The precise angles formed between thelinear slot 36 and the first and second flange portions differaccordingly, but the general symmetric relationship does not.

This concludes the description of the preferred embodiments of thepresent invention. From the above, it can be seen that there has beenprovided an improved mandrel arrangement to mount pipe machining toolsfor rotation relative to an open end of a pipe elbow or other bend,which may be used in a shop or in the field to quickly, accurately andeconomically machine an end of a pipe bend having either both ends openor one end open and the other welded to a run of pipe. In the case of apipe bend having two open ends, the ends may be similarly machinedrelative to two axes, repectively, having a predetermined angularrelationship. This is made possible by the fact that the main frame ofthe mandrel arrangement need not be removed or adjusted relative to thepipe bend between the operations on the two ends.

Those skilled in the art may find variations and adaptations of thepresent invention and the appended claims are intended to cover all suchvariations and adaptations falling within the true scope and spirit ofthe invention.

I claim:
 1. A mandrel for mounting a pipe machining tool for rotationrelative to at least one end of a pipe bend to be machined, whichcomprises:a frame means having a main portion and first and secondflange portions fixed to opposite ends of said main portion, an outersurface of said first flange portion in a first plane, an outer surfaceof said second flange portion in a second plane intersecting said firstplane at a predetermined angle, said frame positionable within said pipebend with said outer surface of said first flange portion adjacent to afirst end of said pipe bend and said outer surface of said second flangeportion adjacent to a second end of said pipe bend; locking meansconnected to said frame and adjustable between a first radiallyretracted condition in which said frame is free for movement relative tosaid pipe bend, and a second radially extended condition in which saidframe exerts an outward force against the interior of said pipe bend tofrictionally retain said frame against movement relative thereto;mandrel shaft means adapted to receive said pipe machining tool forrotation about the axis of said mandrel shaft means; and means foradjustably mounting said mandrel shaft means to at least one of saidfirst and second flange portions of said frame means to provide saidmandrel shaft means extending substantially perpendicularly outward fromsaid outer surface of said at least one of said first and second flangeportions; whereby said mandrel shaft means may be adjusted topredetermined positions on said frame means to receive said pipemachining tool for rotation thereabout.
 2. A mandrel as recited in claim1 in which said means for adjustably mounting said mandrel shaft meanscomprises an axial threaded portion at one end of said mandrel shaftmeans, a first central opening in said outer surface of said firstflange portion and a first nut adapted to engage said axial threadedportion, said first central opening having a substantially greaterdiameter than said axial threaded portion and adapted to receive saidaxial threaded portion in a direction perpendicular to said outersurface of said first flange portion for passage therethrough to aposition of engagement with said first nut, whereby different positionsof said axial threaded portion relative to said first central openingwithin a first radial plane correspond to said predetermined positionsof said mandrel shaft means on said frame.
 3. A mandrel as recited inclaim 2 in which said first nut is mounted to said frame and isrestrained thereby against all movement except substantiallytranslational relative movement parallel to said first radial plane,said first nut being carried by said axial threaded portion as it movesbetween said different positions for the condition of said mandrel shaftmeans mounted to said first flange portion.
 4. A mandrel as recited inclaim 3 wherein said predetermined angle is 90 degrees.
 5. A mandrel asrecited in claim 3 which includes a centering unit adapted to beslidingly received on said mandrel shaft means, having at least threesimilar centering vanes extending longitudinally of and radially fromsaid mandrel shaft means and adapted to engage at least one of saidfirst and second ends of said pipe bend for said centering unit receivedon said mandrel shaft means and pressed toward said pipe bend, and tourge said mandrel shaft means toward the center of said at least one ofsaid first and second ends of said pipe bend.
 6. A mandrel as recited inclaim 5 wherein the outer radial extremity of each of said three similarcentering vanes near one end is longitudinally tapered toward the axisof said centering unit to engage the radially inner edge of said atleast one of said first and second ends of said pipe bend.
 7. A mandrelas recited in claim 6 wherein each of said three similar centering vanesis undercut at its other end to form a longitudinal inward facingtapered surface which progresses outward from the axis of said centeringunit in the direction of said other end and is engagable with theradially outer edge of said at least one of said first and second endsof said pipe bend.
 8. A mandrel as recited in claim 3 which includes alocating plate removably attached to said second flange portion adjacentsaid second end of said pipe bend such that a portion of said locatingplate abuts said second end of said pipe bend to locate said framerelative thereto.
 9. A mandrel as recited in claim 3 wherein saidlocking means comprises a screw thread mechanism adapted to force atleast one movable locking element against the interior of said pipebend.
 10. A mandrel as recited in claim 9 wherein said screw threadmechanism comprises two movable locking elements connected by a singlebolt for actuation of said movable locking elements in oppositedirections by rotation of said single bolt to bear against the interiorof said pipe bend.
 11. A mandrel as recited in claim 10 wherein theangles formed between the axis of said single bolt and said outersurface of said first flange portion is substantially equal to thatformed between said axis and said outer surface of said second flangeportion.
 12. A mandrel as recited in claim 9 in which said means foradjustably mounting said mandrel shaft means includes a second centralopening in said outer surface of said second flange portion and a secondnut adapted to engage said axial threaded portion, said second centralopening having a substantially greater diameter than said axial threadedportion and adapted to receive said axial threaded portion for passagetherethrough to a position of engagement with said second nut, wherebyvarious positions of said axial threaded portion relative to said secondcentral opening within a second radial plane correspond to saidpredetermined positions of said mandrel shaft means on said frame.
 13. Amandrel shaft means as recited in claim 12 in which said second nut ismounted to said frame and is restrained thereby against all movementexcept substantially translational relative movement parallel to saidsecond radial plane, said second nut being carried by said axialthreaded portion as it moves between said various positions for thecondition of said mandrel shaft means mounted to said second flangeportion.
 14. A mandrel as recited in claim 13 wherein said predeterminedangle is 90 degrees.
 15. A mandrel as recited in claim 14 which includesa generally circular locating plate removably attached to said secondflange portion adjacent said second end of said pipe bend such that saidgenerally circular locating plate abuts said second end of said pipebend to locate said frame relative thereto.
 16. A mandrel as recited inclaim 15 wherein said generally circular locating plate is removablyattached to said second flange through a central bolt engageable withsaid second nut and includes a plurality of projections which areadjustable in length and are positioned to space a portion of saidgenerally circular locating plate a desired distance from said secondend of said pipe bend, whereby the orientation of said frame relative tosaid second end of said pipe bend may be varied.
 17. A mandrel asrecited in claim 16 wherein said mandrel shaft means includes a radialflange adjacent said axial threaded portion and positioned such that thelower surface of said radial flange abuts said outer surface of one ofsaid first and second flange portions for said mandrel shaft meansmounted to said one of said first and second flange portions, wherebysaid mandrel shaft means is maintained perpendicular to said outersurface.
 18. A mandrel as recited in claim 17 wherein said radial flangeincludes an eccentric pin projecting downward from said lower surface toengage an opening in said outer surface to prevent said mandrel shaftmeans from rotating in a mounted condition on said frame.
 19. A mandrelas recited in claim 18 wherein said outer surfaces of said first andsecond flange portions are essentially circular.
 20. A mandrel asrecited in claim 19 wherein said first and second flange portionsinclude a plurality of blunt radially outward projections adapted tocontact the interior of said pipe bend for the condition of said framewithin said pipe bend, and thereby to space said frame therefrom.
 21. Amandrel as recited in claim 20 wherein a portion of said mandrel shaftmeans is externally threaded to operatively engage said pipe machiningtool.
 22. A method of mounting a pipe tool for rotation relative to apipe bend for performing a machining operation thereon whichcomprises:placing a mandrel support frame into a first open end of saidpipe bend such that a first outward facing surface portion of saidmandrel support frame is adjacent said first open end; locking saidmandrel support frame in place relative to said pipe bend; looselyengaging a threaded section of a mandrel shaft means with a firstcaptive nut within said mandrel support frame to provide said mandrelshaft means projecting perpendicularly from said first outward facingsurface portion and able to move between a plurality of predeterminedpositions thereon; centering said mandrel shaft means relative to saidfirst open end; locking said mandrel shaft means in place relative tosaid pipe elbow by tightening said threaded section into said captivenut; and mounting said pipe tool for rotation relative to said mandrelshaft means.
 23. The method of claim 22 in which the step of centeringsaid mandrel shaft means comprises sliding a centering device havingsurfaces tapered relative to its axis over said mandrel shaft means to aposition wherein said tapered surfaces engage said first open end tourge said mandrel shaft means toward the center of said first open end.24. The method of claim 22 in which the step of locking said mandrelsupport frame in place relative to said pipe bend comprises actuating athreaded mechanism to urge at least one locking element against theinterior of said pipe bend to frictionally retain said mandrel supportframe against movement relative thereto.
 25. The method of claim 24 inwhich the step of placing a mandrel support frame into a first open endof said pipe bend includes the steps of attaching a locating plate tosaid mandrel support frame from a second open end of said pipe bend andorienting said mandrel support frame relative to said pipe bend toprovide said locating plate abutting said second open end, whereby saidmandrel support frame is properly located relative thereto.
 26. Themethod of claim 25 in which the step of centering said mandrel shaftmeans comprises sliding a centering device having surfaces taperedrelative to its axis over said mandrel shaft means to a position whereinsaid tapered surfaces engage said first open end to urge said mandrelshaft means toward the center of said first open end.
 27. The method ofclaim 26 wherein the step of placing a mandrel support frame into afirst open end of said pipe bend includes orienting said mandrel supportframe such that a second outward facing surface portion of said mandrelsupport frame is adjacent a second open end of said pipe bend.
 28. Themethod of claim 27 which further includes the steps of:disengaging saidshaft means and said locating plate from said mandrel support frameafter the machining operation on said first open end has been completed;loosely engaging said threaded section with a second captive nut withinsaid mandrel support frame adjacent said second open end of said pipebend, to provide said mandrel shaft means projecting perpendicularlyfrom said second outward facing surface portion; centering said mandrelshaft means relative to said second open end; locking said mandrel shaftmeans in place relative to said pipe bend by tightening said threadedsection into said second captive nut; and mounting said pipe tool forrotation relative to said mandrel shaft means.